Process for manufacturing olefins and diolefins



nited States Patent O PROCESS FOR MANUFACTURING OLEFINS AND DIOLEFINS Henry R. Linden, Franklin Park, Jack M. Reid, Villa Park, and Wilford G. Bair, Chicago, Ill., assignors t Institute of Gas Technology, Chicago, lll., a corporation of Illinois Application March 22, 1956, Serial No. 573,124

7 Claims. (Cl. 260-683) t This invention relates to an improved process for making ethylene and other olenic hydrocarbons by thermally cracking petroleum oils and similar liquid or liqueable fossil fuels. A primary object of the invention is to provide a process of this kind characterized by greatly increased yields of oleiins from a wide range of starting materials or feed stocks.

Another object is to provide a process for thermally cracking the feed stock in the presence of hydrogen, wherein the hydrogen is derived from the cracking process itself in the form of a hydrogen-rich tail gas, which remains after removal of the desired olefins and diolens (from the make gas.

The invention consists of dispersing the feed stock in hydrogen, or a hydrogen-rich carrier gas, which has been preheated to cracking temperature, and subsequently cracking the dispersed feed stock under carefully controlled conditions. For optimum yields of all oleiinic and diolenic products, total pressures must not exceed 2O p.s.i.g., and low partial pressures attained by high steam dilutions are favorable. The severity of cracking may be adjusted, by variation of the average cracking temrperature and feed rates, to give optimum yields of the desired olens. At feed rates resulting in residence times from l to 5 seconds, propylene, butylene and butadiene production will be favored at temperatures below 1400 F., and optimum total olefin yields will be obtained at 1400-1600" F. At l6001800 F. and over one second residence time, olefin yields will consist primarily of ethylene. When using the low-cost, high molecular weight, high carbon-to-hydrogen ratio feed stocks such as residual petroleum or shale oils and coal or lignite tar residues, the process is carried out preferably in a cyclic regenerative cracking apparatus wherein a major portion of the feed stock is introduced counter-current to the flow of preheated hydrogen-rich carrier gas. Cyclic operation provides a simple and economic method of handling carbon deposited in all cracking operations. The increased yields in olefins and diolens resulting from our process are remarkable and not at all expected, since one would predict that the presence of hydrogen would reduce the yield of unsaturated compounds. However, it was found that the total conversion of liquid fossil fuels such as petroleum oils, to gaseous hydrocarbons and especially olens and diolens, was much greater when the feed was contacted with highly preheated hydrogen-rich carrier ice gas, than when the feed and the hydrogen gas were brought to cracking'temperature together. For example, cracking of a low cost petroleum oil (residual oil) at 1400 F. and 3-5 seconds residence time in a cyclic regenerative apparatus after dispersing the oil in hydrogenrich carrier gas (equivalent to 45-50 standard cubic feet of pure hydrogen per gallon of oil) flowing countercurrent to the oil, resulted in increases in ethylene production of over 50% and more than doubled the production of propylene, butenes and butadiene, as compared with the same process practiced without use of preheated hydrogen-rich gas. The net production of gaseous constituents was increased by approximately 50% and the production of tar and coke correspondingly reduced. With distillate oil, an approximate 50% increase in ethylene production was obtained, using hydrogen-rich carrier gas preheated to 1650 F., at 16004700 F., 2-4 seconds and the equivalent of 45-50 standard cubic feet of pure hydrogen per gallon of oil. When these feed stocks and hydrogen were introduced into a tube furnace without preheating of the hydrogen, no significant change in olen and diolen yields was observed under similar operating conditions.

The feed stocks suitable for use in the process of the invention may be described broadly as liquid or liqueable fossil fuels which term, when used in this specication and in the appended claims, is intended to include propane, hutane, liquefied petroleum gases (LPG), petroleum oils (distillate and residual), shale oils and liquid products obtained in the carbonization of solid fuels. Except for some constituents in shale oils and carbonization products, these materials all fall largely within the chemical class of hydrocarbons. One of the important advantages of the present process is that it utilizes a wide variety of feed stocks including those which are very low in cost. The feed stock is preferably preheated and then introduced in the form of droplets, a finely-divided mist, or in vapor form, into a stream of hydrogen or hydrogen-rich carrier gas which has been preheated to a temperature of from 1200 to l800 F. The hydrogen content o-f the hydrogen-rich gas (referred to herein as pure hydrogen) should be in excess of 50%. The ratio of pure hydrogen in the carrier gas to feed stock will range up to standard cubic feet per gallon. It will be understood, of course, that the optimum ratio of hydrogen to feed stock will vary in accordance with the carbon-to-hydrogen ratio of the feed stock. Generally, the amount of hydrogen required for optimum olefin production increases proportionally to the carbon-to-hydrogen ratio of the feed stock up to a maximum of 100 standard cubic feet per gallon. Beyond this point hydrogenation of the olelins and diolens will occur under the prevailing cracking conditions. We have found that for petroleum feed stocks from 30 to 60 standard cubic feet of hydrogen per gallon is a practical range when residual product gas is the source of hydrogen.

Preferably, the feed stock is sprayed countercurrent to the flow of the heated hydrogen-rich stream into a suitable cracking vessel maintained at a temperature of from` 13.00to 1,800" F. (such asa, generator of a cyclic oil gas set) to produce a uniform dispersion of liquid droplets or vapor throughout the gas. The gas stream carrying the liquid droplets of feed stock or containing vaporized feed stock is then cracked at a pressure ranging from subatmospheric up to 20 p.s.i.g. at a residence time which must not exceed 10 seconds and preferably should be less than seconds. The cracking vessel or vessels contain no catalyst, the cracking being carried out entirely by heat. Carrier steam in substantially quantities may be used in addition to the hydrogen-rich gas to control residence time, to sweep the reaction products from the cracking vessel, and to reduce the partial pressure of the reacting hydrocarbons. The quantity of steam may range up toten; times the volume of hydrogen confined in the hydrogen-rich; gas. The upper limit will vary with the capacityof the; apparatus for transferring heat t0 the reactants and itspermeability to gas ow.

Upon cracking of the feed stock in the presence of hydrogen, product gas is formed which contains from 25-45%. hydrogen, 25-35% methane, 2-8% ethane, 15-25% ethylene, 2-10% propylene, l-5% butenes and butadiene, and smaller concentrations of other gaseousV hydrocarbons. Benzene and toluene concentrations depend on the efficiency of the liquid condensing system, while dilution with products of combustion (nitrogen and carbon dioxide) depends on the operation of the cracking apparatus. Normally, the stable product gas will have a heating value of 900-1200 B.t.u. per standand cubic foot and a specific gravity of 0.5 to 0.75 on an inert-free basis.

In a preferred form of the invention, after the olelins and diolens are removed from the make gas, the tail gas remaining is recycled into the system as the hydrogenrich carrier gas. Thus, itis possible, in accordance with the present process, to generate within the process itself suiiicient hydrogen-rich gas to serve as the carrier and hydrogen atmosphere during cracking of the feed stock. High methane and ethane concentrations of the hydrogenrich carrier gas are not unfavorable to the process, but any significant amount of olelins and diolefins must be avoided to prevent suppression of olefin and dioleiin formation during cracking of the feedstock. We prefer to use a hydrogen-rich gas containing not more than about 1% olefins and dioleiins (see runs l1, 18 and 19 in table below).

A suitable apparatus for practicing the process of the invention is illustrated in the single figure of the drawing, which shows diagrammatically a four-shell cyclic regenerative apparatus, and the flow of materials through the apparatus. The unit consists of four interconnected shells 21, 11, 12 and 22. The vessels 11 and 12 are the No. l and No. 2 generators. They are interconnected bya crossover 14 near the upper ends thereof and contain a few courses of checkerbrick 16 near the lower end thereof. Vessels 21 and 22 are the No. 1 and No. 2 regenerators. These vessels connect to the lower end of the adjacent generator through identical conduits 18 and 20. The vessels are refractory lined to resist elevated temperatures. The regenerators 21 and 22 are lled with refractory shapes 25 which are capable of absorbing and releasing heat to uids passing therethrough. A pair of tar receivers 24 and 26 connect to conduits 18 and 20, one for each generator-regenerator pair. They are joined to the conduits by means of Ts 27, 29. Heat oil burners and make oil nozzles (not shown) are located in the top of each generator for purposes of spraying these materials into the generators. Make steam and purge steam connections from common supply line 53 connect to the top of each of the regenerators through vertical pipes 54, 56.

Ail for the purpose of burning carbon and tar which is laidV down in the generators during cracking, and for combustion of heat oil, is supplied from blower 46 through conduit 48. BranchlinesSt) andSZ- connect line.

48 through suitable valves to the pipes S4 and 56. Ex-

haust stacks 55 and57 connect to the tops of regenerators,

21 and 22. The make gas leaves the set through conduits 30 and 32 connecting to the side of tarpots 24 and 26, respectively. Suitable pressure regulator 34 is inserted in the line 32 for purposes of regulating the pressure within the generators and regenerators. First and second stage condensers 36 and 38 are provided for condensing steam and light oils in the make gas. The product gas is discharged from the lower end of second stage condenser 38 through line 40 and meter 42. To provide cool tar for quenching make gas in the tarpots, a circulating system is employed which permits tar to ow from the tarpots through lines 31, 33 and 35 to the tar cooler 44 and back to the pots through line 37. The tar is collected through vertical drain lines 39 and 41. Water for quenching the product gas issuing from` the conduit 18 is provided through lines y43 and 4S which connect just below the Ts 27, 29. connecting the tarpots to conduits 18 and 20.

The gas-tired heater 58 is-provided for preheating the make oil, or other liquid feed stock, prior to introduction into the setv through line 60. The system, of course, is equipped with-suitable valves and controls which permit tiexibility for changing the cycle length as desired. Details with respect to the construction of this four-shell set and other cyclic sets suitable for use in practicing the present invention are shown and described in an application of Elmore S. Pettyjohn and Henry R. Linden, Serial No. 424,012, led April 19, 1954.

In cracking fossil fuels in accordance with this invention, using the apparatus illustrated in the drawing, the iirst step is a forward make cycle during which hydrogenrich carrier gas and make steam, if desired, enter the top` of the regenerator 21 through which they ow downwardly to absorb heat from the regenerator which has previform downwardly as the preheated hydrogen-rich gas ory mixture of hydrogen and steam` ows upwardly. Cracking is initiated in generator 11 and the products pass over through crossover 14 into generator 12 where cracking completed. Additional' make oil may be introduced at the top of the generator 12 if the desired cracking reactions can be completed before the entire reaction mass leaves generator 12 through conduit 20. The cracking time and the partial pressure of the reactive constituents (hydrocarbons and hydrogen) may be conveniently controlled by adjusting the volume of steam which serves to sweep the reactants and product gases through the set. The products of cracking are withdrawn through the T 29 in the tarpot 26 where they are quenched with cooled recycle tar sprays to reduce the temperature to approximately 3D0-600 F. Condensed tar, which is deposited in the bottom of the pot, is continuously circulated through the cooler 44 and back up to the top of the pot through line 37 for this purpose. A suitable method and apparatus for cooling gases with tar and for recovering tar in dry form is shown and described in Patent No. 2,719,819 to Elmore S. Pettyjohn. Quench water from line 45 may be used to supplement the tar if the temperature is not reduced sufficiently. From the tarpot the make gas passes through the back pressure regulating valve 34 into the condensing system. At the conclusion of the make period, which may range from less than one to over ve minutes. the bypass valve 66 is opened, bleeding the pressure within the set down to essentially atmospheric.

The make period is followed'by a steam purge wherein steam from the supply source 53 enters the top of the regenerator 21 through thepipe 5 41fo1lowing the same path as the make products just described. The valve in the stack 57 is opened and the blast is started in the same direction as the make. This period is initiated by bringing air into the top of the regenerator 21 through `v the line 50. The introduction of air into the set causes v flow downwardly through generator 12 through connector conduit 20, and upwardly through regenerator 22 giving up their heat to the checkerbrick therein, and are discharged from the stack 57. Depending upon the particular type of feed stock employed, the carbon lay-down may be large or it may be almost negligible. In using the light hydrocarbons as feed stock, the carbon laydown will be held to a minimum, and in such case it is necessary to inject considerable heat oil into the generator 12 in order to bring the generator and the checkerbrick in regenerator 22 up to the desired temperature for heating the incoming hydrogen-rich gas. At the conclusion of the blast period, which may require from less than one to over five minutes, the stacks arey reversed and the blast gas is purged from the set in the reverse direction with the purge steam entering the regenerator 22 and being discharged through the stack 55 after traversing the entire set. The make period in the opposite direction is then initiated. Hydrogen or hydrogen-rich gas is introduced from lines 61, 56 into the top of regenerator 22 where it picks up heat and ows through the conduit 20 upwardly through the generator 12. Simultaneously liquid fuel or make oil is introduced in the form of a spray at the top of the generator 12 countercurrent to the ow of the hydrogen or hydrogenrich gas. Cracking is initiated in the No. 2 generator 12 and the cracking products together with uncracked make oil, which is thoroughly dispersed in the hydrogenrich gas, passes through the crossover 14 into the generator 11 where the cracking reaction is completed. Additional make oil can also be introduced in generator 11. The make gas flows through conduit 18, T 27, tarpot 24, line 30 and into the condensing system. The process is then repeated in the reverse direction, as previously described.

It will be noted that in accordance with this process none of the make products pass through the regenerators. The make gas passes from the bottom of the generators into the tarpot and is discharged therefrom through either line 30 or line 32 into the condensers. Consequently, all deposited coke and pitch is confined to the generators. to obtain extremely high efficiencies in regenerator operation and avoid smoke at the start of the blast without the use of the air purge.

A typical 8 minute operating cycle giving the valve sequence for gasification of either No. 2 furnace oil or reduced crude oil in the apparatus shown in the drawing is given below:

TYPICAL CYCLE OF VALVE SEQUENCE @senese Valve function: Seconds No. 2'heat oil close 214 Noll air blast close 217 No. 2 stack close 217 No. 1 stack open 217 No. Zpurge steam open 217 No. 1 stack close 233 No. 2 purge steam close 241 No. 2 make steam open 241 No. 2 make oil open 241 No. 2 hydrogen open 243 No. 2 hydrogen close 323 No. 2 make oil close 324 Bypass open 324 No. 2 purge steam open 351 No. 2 make steam close 357 No. 1 stack open 361 Bypass close 364 No. 2 purge steam close 365 No. 2 air blast open 365 No. 1 heat oil open 368 No. 1 heat oil close 454 No. 2 air blast close 457 No. 1 stack close 457 No. 2 stack open 457 No. l purge steam open 457 No. 2 stack close 473 No. 1 purge steam close 482 No. 1 make steam open 482 No. 1 make oil open 482 period; the blast following the make period may proceed in the opposite direction from the preceding make; the set may be filled or pressurized with steam and/or hydro- 'gen before the make; and stack valve reversal and steam purge techniques may be varied to be convenient for the apparatus or exact operating cycle employed. Conven- The absence of fouling makes it possible 50 tional fluid bed or moving bed operation, in which the heat requirements are supplied by a stream of a suitable heat transfer medium which is reheated in a separate Vessel or zone, may be substituted for cyclic operation. Continuous or semi-continuous operation in tube furnaces or other externally heated reactors, can also be used, especially with the lower molecular weight, lower carbonhydrogen weight ratio feed stocks, as long as the hydrogen-rich carrier gas is preheated to 1200-1800 F. before contacting the feed stock, intimate mixing of feed stock and preheated hydrogen is effected, and the reaction mass is maintained at 13001800 F. for not over 10 seconds at pressures not exceeding 20 pounds per square inch Y gauge.

Utilizing the cycle set forth above, test runs were made in the apparatus described using distillate oil and reduced crude oil as the feed stocks. A direct comparison was made between the cracking process utilizing preheated hydrogen carrier gas and cracking without any hydrogen whatsoever. The reduced crude oil was characterized by 23 API, 7.0% carbon-to-hydrogen ratio, and 5.3% by weight Conradson carbon residue. The distillate oil had the following specifications: 34 API, 6.6% carbon-tohydrogen ratio, and 0% by weight Conradson carbon residue. Run 7 on the distillate oil and runs 16 and 17 on the reduced crude oil were without hydrogen. Run l1 for distillate oil and runs 18 and 19 for the reduced crude oil were with hydrogen. The table set forth below gives the complete operating conditions and results for cracking of these oils, includinga detailed analysis of the make gas, ue gas and the process hydrogen (hydrogen-rich gas) which served as the carrier gas.

Operating result from cyclic four-shell high-Btu. oil gas pilot plant on 34 API, 6.6 C/H ratio, 0 wt. percent Conradson carbon residue distillate oil and 23 API, 7.0 C/H ratio, 5.3 wt. percent Conradson carbon residue reduced crude oil Distillate oil Reduced crude oil Run NO 7 11 16 19 17 18 Process feeds:

Make oil used, gai/hr 54.0 57. 50. 1 50. 0 51. 0 46.8 Make steam used, 1b. r 218. 5 216. 9 202. 6 214. 7 140. 3 178. 7 Heat oil used, gal./hr 10. 53 10. 79 8.55 8.75 8.73 8. 52 Blast air used, s.c.f./hr 33, 540 28, 880 28,300 27, 610 27,200 26, 500 Purge steam used, lb./hr 285. 5 195. 2 211. 7 205. 9 211. 7 205. 9 Process hydrogen used, s.c.f.lhr 0 3, 015 0 2, 747 0 2, 802 Process hydrogen used, s.c.f./ga1 0 52. 5 0 54. 9 0 59. 9 Operating conditions:

Temperatures, F.-

Average cracking 1, 657 1.647 1, 530 1. 432 1. 508 11490 N o. l generator:

T 388 288 360 334 359 Betto 1, 772 1, 630 1, 364 1, 320 1, 449 1, 348 Maximum make pre p.s.i.g. 7 10.5 6 8. 5 7 7 Mean effective pressure, atm. abs 1. 23 1. 33 1. 18 1. 27 1. 22 1. 22 Maximum inert free make gas partial pressure, atm. abs 0.65 0.95 0. 66 0.89 0. 81 0 85 Mean inert free make gas partial pressure, atm. abs 0. 55 0. 75 0.56 O. 72 D. 68 0.71 Operating results:

Make gas- S.c.f./hr 3, 983 6, 747 4, 285 6, 886 4, 727 6. 266 sat1/gal., gross 73. 76 118. 3 85.55 137. 6 92.62 133.9 Calculated B.t.u. recovery- M B.t.u./gal., gross 79. 03 121. 9 94.02 155. 4 87. 56 144.8 M Btu/gal., net 79. 03 102.8 94.02 135.1 87. 56 123. 5 Make oil usedgaL/M c.f 13. 56 8. 45 11. 69 7. 27 10. 80 7. 47 gaL/MM B.t.u., gross 12.65 8. 10.64 6.44 11.42 6.90 gai/MM B.t.u., net 12. 65 9. 73 10.64 7.40 11. 42 8.10 Heat oil usedgaL/M ci 2. 64 1. 60 2. 00 1. 27 1. 85 1. 36 gah/MM B.t.u., gross 2.47 1. 1.82 1.13 1.95 1.26 gaL/MM B.t.u., net 2. 47 1.84 1.82 1. 29 1. 95 1. 47 Total oil usedgal/MM Btu., gross 15. 12 9. 75 12. 46 7. 57 13. 37 8.16 gaL/MM B.t.u., net 15. 12 11. 57 12.46 8.69 13.37 9. 57 Product yields, netthylene:

sci/gal., make oil 13.28 19. 30 19.08 28.76 16.86 26. 55 sail/gal., total oi.l. 11. 11 16.23 16.30 24.48 14. 42 22. 46 Weight percent, make o 13. 87 20.03 18. 50 27.90 16. 35 25. 75 Weight percent, total oil 11. 16.84 15.81 23. 74 13.98 21.78 Propylene:

sci/gal., mnke oil 3. 69 4. 14 2.91 9.03 0. 65 6.37 s.c../gal., total oil 3.09 3.48 2. 48 7. 68 0. 55 5. 39 Weight percent, make o 5. 74 6.40 4. 23 13. 13 0.94 9. 26 Weight percent, total oil 4. 5. 38 3. 61 11.18 0. 81 7. 84 Butenes:

sci/gal., make oil 0. 22 0. 49 0.17 1. 38 0. 28 1. 47 sci/gal., total 0i1 0. 19 0. 41 0. 15 1.17 0. 24 1. 25 Weight percent, make 0 0. 46 1. 01 0. 33 2. 67 0. 54 2. 86 Weight percent, total oil 0. 39 0.85 0. 28 2. 27 0. 46 2. 42 Butadiene:

s.c.f./ga1., make oil 0.59 1. 13 0.68 2. 20 0. 46 2.01 sei/gal., tota1oi1- 0.49 0. 95 0. 58 1. 87 0.40 1. 70 Weight percent, make o1 1. 22 2. 31 1. 28 4. 12 0. 87 3. 76 Weight percent, total oil 1. 01 1. 95 1. 09 3. 51 0.76 3. 18

Make gas properties:

Composition, v01. percent- Hydrogen 23.3 35. 1 20. 2 28.3 28.2 29. 5 43. 3 30.1 36. 9 28. 9 37. 8 29. 2 2. 7 4. 5 2. 8 4. 3 1. 5 4. 3 0.1 0.3 0.1 0.4 0.0 0.1 18.0 16.4 22. 3 21. 1 18. 2 a). 1 Propylene 5.0. 3. 5 3. 4 6. 6 0.7 4.8 Butenes and higher- 0. 3 0. 7 0. 2 1. 0 0. 3 1. 1 Butadiene 0. 8 1. 0 0. 8 1. 6 0. 5 1. 5 Pentadiene- 0. 2 0. 3 0. 2 0. 5 0. 2 0. 3 Acetylene. 0.6 0. 1 0. 3 0. 1 0. 7 0. 1 Benzene 1. 4 1. 9 2. 7 1. 1 2. 4 1. 7 Toluene and higher- 0. 2 1. 1 0. 9 0. 8 0. 4 0. 8 CO: 1.8 1.5 1.2 1.2 2.0 1.5 C0 and N1 2.3 3.5 8.0 4.1 7.1 4.9

Total 100. 0 100.0 100. 0 100. 0 100. 0 100. 0 Heating value, B.t.u./s.c.f. 1, 071 1, 031 1, 099 1, 129 945 1, 082 Specific gravity, 6151.00., ...vn... 0. 659 0. 641 0. 741 0. 711 O. 636 0. 698

assaasa Distillate oil Reduced crude oil Run No 7 11 16 19 17 18 Inert-'ee product gas properties:

Composition, vol. percentydrogen 24. 3 36. 9 22. 3 29.l 9 31. D 31. 6 Methane 45. 1 31. 7 40. 6 30. 5 41. 6 31. 2 Ethane 2 8 4. 7 3. 1 4. 5 1. 6 4. 6 Propane and higher 0.1 0. 3 0.1 0.4 0. 0 0. 1 thylene 18. 8 17. 3 24. 6 22. 3 20. 1 21. 5 Propylene and higher 5. 5 4. 4 3. 9 8. 1 1. 1 6.3 Diolens and acetylene 1. 7 1. 5 1. 4 2. 3 1. 6 2. 0 Benzene 1. 5 2. 0 3.0 1. 2 2. 6 1. 8 Toluene and higher. 0. 2 1. 2 1. 0 0. 8 0.4 0. 9

Total 100. 0 100. 0 100. 0 100.0 100.0 100. 0 Heating value, BJ' 11 ,le f f 1,120 1, 078 1, 210 1, 192 1, 038 1,157 Specific gravity, air=1.00 0. 649 0. 612 0. 710 0. 690 0. 588 0. 667

Flue as anal sis vol. ercent:

ogn y p 8.3 8.9 8.9 6.7 9.7 7.8 CO 0.0 0.0 0.0 0.4 0.0 0.0 Oa 7. 1 5. 3 6.8 4. 7 4. 5 6.0 N e 84. 6 85. 8 84. 3 88.2 85. 8 86. 2

Total 100. 0 100. 0 100. 0 100. 0 100. 0 100. 0 Proiss hydggen prrlipertles: t

om os ion vo ercen liydrnm'. p s1. 1 19. 6 so. o Methane 3. 8 7. 5 7. 6 Ethane and higher 0. 7 1. 2 0. 5 Ethylene 0. 2 0. 5 0. 6 Propylene and higher 0. 3 0. 1 0. 1 Aromatics 0. 3 0. 2 0. 0 i 3. 0 2.9 2. 8 OO 3. 2 4. 7 3. 4 N 1. 4 3. 3 5. 0

Total- 100. 0 100. 0 100. 0 Heating value, B t 11 ,ls f f 364 368 363 Specific gravity, air=1.00 0.197 0.244 0. 235 Material balance:

Gas, Weight percent 49. 2 67. 3 54. 5 82. 0 75. 9 Tar, Weight percent 1- 45. 7 30. 6 39. 3 17. 8 22. 0 Ooke, weight percent 2 5. 1 2.1 6. 2 0.2 2. 1

1 By difference.

In comparing runs 7 and 11 it will be noted that the ethylene yield was increased from 13.87% to 20.03% of make oil. Similar improvements were shown for reduced crude, the yield being increased from 18.50% to 27.90% (runs 16 and 19) and from 16.35% to 25.75% (runs 17 and 18). The increase in propylene was particularly great in cracking of reduced crude oil as a cornparison of runs 16 and 17 with companion runs 18 and 19 will indicate. The difference between runs 17 and 18 is almost tenfold. Greatly increased yields of butenes and of butadienes were also obtained.

The heating values set forth in the table above indicate that the gas produced in accordance with the present process is suitable as a high B.t.u. fuel gas.

It will be understood that the foregoing examples are merely illustrative of the invention and that similar results may be obtained utilizing different feed stocks, apparatus and other operating conditions within the limits set forth in this specification.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A process for making a gas rich in olefins and diolens from a feedstock taken from the group consisting of liquefied petroleum gases and liquid fossil fuels, which comprises introducing a stream of hydrogen-rich gas containing at least 50 volume percent hydrogen and not more than about 1% olens and diolefins, preheated to 1200 to 1800o F., into a cracking vessel maintained at cracking temperature and at a pressure ranging from subatmospheric to 20 pounds per square inch gauge, dispersing said feedstock in finely divided form in said hot, gaseous stream at a rate of one gallon per to 100 standard cubic feet of pure hydrogen to crack the feedstock as it flows through the cracking vessel to form a gaseous product containing oleiins and dioleiins, the residence time in said cracking vessel not exceeding 10 seconds, and separating said oleiins and dioleiins from said gaseous product.

2. The process of claim 1 wherein said hydrogen-rich gas consists of pure hydrogen.

3. A process for making a gas rich in oleiins and diolefins from a feed st-ock taken from the group consisting of liquefied petroleum gases and liquid fossil fuels, which comprises introducing a stream of hydrogen-rich gas containing at least 50 volume percent hydrogen, preheated to 1200 to 1800 F., into a cracking vessel maintained at cracking temperature and at a pressure ranging from subatmospheric to 20 pounds per square inch gauge, dispersing said feedstock in finely divided form in said hot, gaseous stream `at a rate of one gallon per 30 to 100 standard cubic feet of pure hydrogen to crack the fedstock as it iiows through the cracking vessel to form a gaseous product containing oleiins and dioleiins, methane, ethane and hydrogen, the residence time in said cracking vessel not exceeding 10 seconds, separating said olens and dioleiins from said gaseous product and recycling said residual gas vcontaining at least 50% hydrogen, methane and ethane as said hydrogen-rich gas.

4. A process for making a gas rich in oleiins and dioleiins from a feedstock taken from the group consisting of liquefied petroleum gases and liquid fossil fuels, which comprises introducing a mixture of hydrogen-rich carrier gas containing at least 50 volume percent hydrogen and not more than about 1% oleiins and dioleiins, and diluent steam preheated to 1200 to 1800 F., into a cracking vessel maintained at 1300 to 1800 F. and at a pressure ranging from subatrnospheric to 20 pounds per square inch gauge, dispersing said feedstock in iinely divided form in said mixture of hydrogen-rich carrier gas and steam at a rate of one gallon per 30 to standard cubic feet of pure hydrogen to crack the feedstock as it flows through the cracking vessel at residence times of 1 to 10 seconds into a product gas containing oleiins and dioleiins, and separating said olefns and dioleiins from said gaseous product.

5. A process for making a high B.t.u. fuel gas from a feedstock taken from the group consisting of liquefied petroleum gases and liquid fossil fuels, which comprises introducing a stream of hydrogen-rich gas containing at least 50 volume percent hydrogen and not more than about 1% of olens and diolelins, preheated to 1200 to 1800 F., into a cracking vessel maintained at cracking temperature and at a pressure ranging from subatmospheric to 20 pounds per square inch gauge, dspersing said feedstock in nely divided form in said gaseous stream `at a rate of one gallon per 30 to 100 standard cubic feet of pure hydrogen to crack the feedstock as it ows through the cracking 4vessel to form said high I]3.t.u. fuel gas.

6. A process for making a lgas rich in oleiins and diolens from a petroleum oil which comprises introducing a stream of hydrogen-rich gas containing at least 50 volume percent hydrogen land not more than about 1% olens and diolens preheated to 1200 to l800 F. into a cracking vessel maintained at a temperature of 1300 to l800 F. and at a pressure ranging from subattnospheric to 20 pounds per square inch gauge, spraying said oil into said hot gas stream at a ratio of 30 to 100 standard cubic feet of pure hydrogen per gallon of oil to crack the oil as it flows through the cracking vessel to form a gaseous product containing olens and diolens having from 2 to 4 carbon atoms, the residence time in said cracking vessel not exceeding 10 seconds, and separating said oleiins and diolens from said gaseous product.

7. A process for making a gas rich in oleiins and diolens from a feedstock taken from the lgroup consiststandard cubic feet of pure hydrogen, said hydrogen-rich gas containing at least 50 volume percent hydrogen, introducing said stream into a cracking vessel maintained at a temperature of 1300 to 1800 F. and pre-pressurized with steam to a pressure not in excess of 20 pounds per square inch gauge, to crack said feedstock as it ows through the cracking vessel to form a gaseous product containing oleins, diolefns, hydrogen, parainic hydro carbons, light aromatics and tar vapors, the residence time in said cracking vessel not exceeding 10 seconds, quenching said gaseous product to condense out said light aromatics, steam and tar vapors, separating the olelins and diolens from the quenched product gases and recycling the gas containing hydrogen and paralinic hydrocarbons for use as said hydrogen-rich carrier gas.

References Cited in the iile of this patent UNITED STATES PATENTS 2,369,281 Chaney Feb. 13, 1945 2,656,307 Findlay Oct. 20, 1953 2,736,685 Wilson et al Feb. 28, 1956 2,768,124 Berg et al Oct. 23, 1956 

1.A PROCESS FOR MAKING A GAS RICH IN OLEFINS AND DIOLEFINS FROM A FEEDSTOCK TAKEN FROM THE GROUP CONSISTING OF LIQUEFIED PETROLEUM GASES AND LIQUID FOSSIL FUELS, WHICH COMPRISES INTRODUCING A STREAM OF HYDROGEN-RICH GAS CONTAINING AT LEAST 50 VOLUME PERCENT HYDROGEN AND NOT MORE THAN ABOUT 1% OLEFINS AND DIOLEFINS, PREHEATED TO 1200* TO 1800* F, INTO A CRACKING VESSEL MAINTAINED AT CRACKING TEMPERATURE AND AT A PRESSURE RANGING FROM SUBATMOSPHERIC TO 20 POUNDS PER SQUARE INCH GAUGE, DISPERSING SAID FEEDSTOCK IN FINELY DIVIDED FORM IN SAID HOT, GASEOUS STREAM AT A RATE OF ONE GALLON PER 30 TO 100 STANDARD CUBIC FEET OF PURE HYDROGEN TO CRACK THE FEEDSTOCK AS IT FLOWS THROUGH THE CRACKING VESSEL TO FORM A GASEOUS PRODUCT CONTAINING OLEFINS AND DIOLEFINS, THE RESIDENCE TIME IN SAID CRACKING VESSEL NOT EXCEEDING 10 SECONDS, AND SEPARATING SAID OLEFINS AND DIOLEFINS FROM SAID GASEOUS PRODUCT. 